This invention relates to fabric condition in compositions which are suitable for softening in the rinse cycle of an automatic household washing machine, and which are especially adapted for use under European laundering conditions. More particularly, the present invention relates to fabric conditioning compositions comprising defined alkanolamine diester and/or triester combination with an acid and optionally a fatty alcohol, which compositions are characterized by superior environmental compatibility relative to conventional tertiary amine or quaternary ammonium fabric softening compositions concomitant with providing improved calcium salt solubilization and reduction of encrustation on treated fabrics.
The combination of organic acid with cationic fabric softener such as amities and quaternary ammonium compounds is extensively disclosed in the prior art. U.S. Pat. Nos. 3,904,359 and 3,954,630 to Ramachandran disclose a fabric treating composition comprising a complexing acid such as citric or maleic acid in combination with a quaternary ammonium compound or amines such as primary tallow and primary coco amine. The function of the acid, as stated in the patents, is to prevent yellowing of fabrics due to build-up of cationic softener and to provide a complexing site for metal ions contained in soils. U.S. Pat. No. 4,828,722 to Steltenkamp and U.S. Pat. No. 4,869,836 to Harmalker disclose multicarboxylic acid complexes of tertiary amines formed from a tertiary amine and a carboxylic acid selected from among citric acid and di and tri carboxylic acids having 21 to 54 carbon atoms. In U.S. Pat. No. 4,832,856 is disclosed a fabric softener composition comprising a combination of carboxylic acid and amities having a long chain alkyl or alkenyl radical
European Patent Publication No. 123,400 to Kardouch discloses detergent compositions containing salts of specified tertiary amities and carboxylic acids which are utilized in the form of modules that pass virtually unchanged through the wash and rinse and then condition the fabric when heated in a dryer. European Patent Publication No. 417,987 describes fabric softening compositions comprised of tertiary amities and carboxylic acids.
Although satisfactory results may be obtained with one or more of these prior art fabric softening compositions, further improvements are needed in terms of being able to provide efficacious fabric softening with a biodegradable cationic fabric softening compound, concomitant with the ability to substantially solubilize and remove mineral encrustation from the fabrics to be treated. This is a particularly important need for European fabric conditioning compositions where the cumulative deposition of mineral salts on fabrics during repetitive laundering in hard water is an acute problem. Moreover, the increased emphasis in Europe on using biodegradable softening compounds which have no toxic effect on aquatic organisms in aqueous effluent streams makes it imperative that conventional softening compounds, most notably, the di-long chain, di-short chain quaternary ammonium compounds be replaced as the softening compounds of choice in commercial rinse-cycle softening compositions with softening compounds which are significantly more compatible with environmental concerns.